The invention relates to a display for informing the operator of a motor vehicle of the level of danger of the instantaneous driving situation.
As traffic density increases, collisions between vehicles following one behind the other occur more frequently as a result of vehicles following too closely or travelling at excessively high rates of speed if visibility is poor. This development highlights the need for a simple and reliable display of the level of danger of the driving situation of a vehicle. There is still a lack of display devices which are capable of providing displays in a way which is appropriate for the specific perception requirements in general traffic and which thus fulfills an essential basic requirement for a high level of acceptance in motorized traffic.
In fact, the technical paper "Autonomous Distance Warning Device in Fleet Trials", published in the journal Forschungsbilanz (Research Reports) 1978 issued by the Bundeminister fur Forschung und Technologie (Federal Minister for Research and Technology) by Verlag TUV Rheinland GmbH on development trends in motor vehicle technology and road traffic discloses a display which is integrated into the dashboard of a motor vehicle for displaying the level of danger of the instantaneous driving situation of a motor vehicle. The display in this case consists of a line of LEDs which are composed of a plurality of segments. The length of the segments which can be illuminated in different colors can be actuated in a variable fashion depending on the level of danger.
This display has the disadvantage that, for its continuous cognitive perception and observation, it excessively tires and distracts the driver of the vehicle. As a result, the driver's attention threshold for the rest of the surroundings and traffic events is significantly degraded.
Furthermore, an electronic parking aid referred to as the "Bosch Parking Pilot" is available which uses, inter alia, an alphanumeric digital display. Next to a distance indication, a simplified arrow symbol can be "intensified" based on the numerically displayed, currently remaining safety distance from an obstacle behind by arranging a greater or lesser number of arrow symbols in a unidimensional fashion. However, this display is incapable of displaying, either generally or gradually, a level of danger which takes into account the instantaneous speed at which the vehicle is travelling.
The object of the present invention is therefore to provide a display which shows the level of danger of the instantaneous driving situation of a vehicle, in a manner that is simple and reliable and takes the vehicle's speed into account.
This object is achieved according to the invention by means of a display which comprises a video screen and a control which processes at least the travelling speed and the distance between vehicles. The display presents a green circular area if the speed and the distance from the vehicle in front are in the permitted, instantaneously safe range. If the vehicle speed exceeds the permitted speed by a first limit amount (for example 5%), or if the distance from the vehicle in front becomes smaller than the distance which the vehicle covers within a first prescribed time period, (for example, two seconds), the display changes gradually from the circular shape, to an elongated area with a shape which extends more horizontally (that is, transversely with respect to the direction of travel) than vertically (that is, in the direction of travel), and the color of the area shown changes from green to yellow.
If the permitted speed is exceeded by a second limit amount (for example 19%), or the distance from the vehicle in front becomes smaller than the distance which the vehicle covers within a second prescribed time period (for example, one second), the display changes to a symbol containing cognitively striking warning information and at the same time the color of the symbol shown changes from yellow to red.
The display which is designed in this manner advantageously uses for the cognitive communication of its information the experience that a circular area is felt to be a positively harmonic shape which it is worth striving to preserve, whilst for example an area which extends horizontally, or has corners or completely covers a display field, is felt to be an impediment which should be avoided.
The advantage of such a display lies in the reduction of information, with simultaneous request for action. If the display changes for example the color of the symbol from green to yellow or from yellow to red, such change indicates to the driver of the vehicle that he should take his foot off the accelerator pedal (as at a traffic light), regardless of whether for example the permitted speed has just been exceeded or the distance from the vehicle in front has become too small.
According to the invention, the area which extends more horizontally than vertically can be substantially elliptical. Furthermore, the display control unit 11 can be constructed such that the degree of deformation (that is, the eccentricity, or the ratio of length to width) of the previously circular area, for example into such an ellipse, corresponds respectively to the degree by which the safe maximum speed is currently being exceeded or the degree by which the optimum, safe distance from the vehicle in front is reduced or undershot.
In addition, the display can also be designed so that, for example, the display of a yellow substantially elliptical area changes, if the second limit amount is exceeded, into for example an ellipse which has a maximum horizontal extent and a minimum vertical extent symbolizing a red danger sign for the driver of the vehicle.
Alternatively, the display of an elliptical area which is still shown as yellow can change to a red warning triangle or square, which may also fill the entire screen. In particular in the last two cases, the corresponding change of shape of the displayed signal can be sudden.
Another embodiment of the display according to the invention indicates the distance or degree of departure from the safety limit by causing the green circular area (indicating that the distance is greater than the safety distance and the vehicle is travelling more slowly than the maximum safe speed) to change its shape into an area which extends more vertically (in the direction of travel) than horizontally, for example into an elliptical area having a vertical major axis. In this manner, this area can also change its shape to a greater extent the greater the safety margin relative to the optimum safe driving situation. For example, the maximum deformation of such a vertical ellipse can correspond to that of the previously mentioned horizontal ellipse.
The signals required for the appropriate actuation of the display are acquired from wheel speed sensors and from sensors which detect the surroundings of the vehicle, for example from a distance-detection radar, an infrared visual range meter or a system which detects the instantaneous coefficient of friction between tire and road and continuously evaluates this information for example in a computer, and processes it to form actuation signals for the display.
At the same time, with available sensor systems, the display can be used to show all physical variables which influence the control of the longitudinal dynamics of the vehicle. For example, the display can derive what it displays as a function of instantaneous distance from the vehicle in front--safety distance; that is, the difference between the current rate of speed of the vehicle and
speed limit/permitted speed PA1 visual range/permitted speed PA1 tire friction/permitted speed.
The individual influencing factors are logically linked with an OR operation. As soon as a component supplies a negative value, the display can change what it displays, for example from green to yellow or from the circular area to the ellipse, etc. If more than one influencing factor simultaneously supplies a negative value, the display determines what it displays according to the respectively most negative instantaneous value.
According to a further embodiment, at least the number of kilometers per hour at which the vehicle is instantaneously travelling can be depicted within the respectively indicated area.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.